1. Field of the Invention
The present invention relates to a monoclonal antibody with the capability of neutralizing enterovirus type 71 infection.
2. Description of the Related Art
Therapeutic monoclonal antibody (mAb) provides a useful and specific tool for curing various infectious diseases and even for some cancers. Using these magic bullets for human, however, those mAbs derived directly from rodent hybridoma may cause severe allergy or immunoresponses. To attenuate or reduce the potential immunogenicity for the therapeutic purposes in human body, each domain of the mAb, except for the variable regions (Fv) which contain CDRs (complementarity determining regions), should be replaced by human counterparts (i.e. constant regions of heavy and light chains). This replacement process is termed humanization or recombination of mAb (see e.g., Boulianne, G. L., et al. (1984) Production of a functional chimeric mouse/human antibody, Nature 312,643-646, incorporated herein as reference by its entirety.)
To humanize a rodent's mAb, variable and constant regions of both heavy and light chains have to be cloned firstly from mouse and human, respectively. Thanks to the advance in molecular cloning technologies, variable regions could be cloned directly by reverse transcription polymerase chain reaction (RT-PCR) from rodent hybridoma using a set of degenerate PCR primers which could amplify DNA fragments between secretory signal sequences and V-J-C junctions. Similar strategy was also used to clone the constant regions of human (see e.g., Morrison, S. L. et al. (1984) Chimeric human antibody molecules; mouse antigen-binding domains with human constant region domains, Proc. Natl. Acad. Sci. USA 81,6841-6855, incorporated herein as reference by its entirety.) FIG. 1 schematically illustrates structures of chimeric monoclonal antibody.
Enterovirus 71 (EV71) belongs to the human Enterovirus A species of the Enterovious gneus within the Piconaviridae family. Since it was discovered in Californa in 1969 and its infection case was first reported in 1974 in United States, EV71 infection has been reported in at least 12 small and large outbreaks throughout the world, including Taiwan.
In 1998, the largest EV71 epidemic reported to date outbreaked in Taiwan (Ho M. et al. (2000) An Epidemic of enterovirus 71 infection in Taiwan. N Engl J Med 341, 929-935), 129,106 cases were reported by sentinel physicians, followed by two smaller epidemics in 2000 and 2001, respectively. Like other types of enteroviral infection, EV71 infection may be asymptomatic or may cause diarrhea, rashes, vesicular lesions on the hands, feet, and oral mucosa (hand-foot-and-mouth disease, HFMD) in young children. Although most of HFMD disease caused by EV71 infection is usually considered a benign disease without central nervous system (CNS) disorders, outbreaks in the Asia-Pacific region, including Japan and Taiwan, appeared with frequent involvements of severe and mortal CNS syndromes such as aseptic meningitis, brainstem encephalitis, acute flaccid paralysis and neurogenic pulmonary oedema.
Since no effective antiviral treatment for severe EV71 infections and no vaccine is available, the only current means to prevent EV71 infection is through avoidance of contact between infected and susceptible individuals.
Accordingly, a monoclonal antibody specific for neutralizing EV71 infection may be an ideal prophylactic treatment for preventing the various debilitating effects or syndromes of the infection by EV71 (Wu C. N. et al. (2001) Protection against lethal enterovirus 71 infection in newborn mice by passive immunization with subunit VP1 vaccines and inactivated virus. Vaccine 20, 895-904.).